Human Rights Watch has called on Nigerian authorities to prosecute security personnel who allegedly killed more than 130 people during sectarian violence last year.
Representatives of the group testified Monday before a judicial commission of inquiry in Nigeria's Plateau state.
In a report released Monday, Human Rights Watch accuses soldiers and police of arbitrarily killing 133 men and boys, nearly all of them Muslim, in the city of Jos last November.
It says most of the killings occurred November 29, the day after clashes between Muslim and Christian mobs killed several hundred people in Jos.
The report says police and soldiers shot unarmed citizens, and lined up victims on the ground before executing them.
Reuters news agency quotes a Plateau state police spokesman (Mohammed Lerama) as saying the accusations are not true.
The judicial commission has been tasked with looking into the causes of the Jos violence and identifying the people or groups responsible.
The violence erupted after the city's Muslim and Christian communities disputed the results of a local election.
Sectarian violence has flared before in Jos. Hundreds of people were killed there during street fighting in 2001.
Plateau State sits in Nigeria's "middle belt" region that separates the country's mainly Christian south from the predominantly Muslim north.
Some information for this report was provided by Reuters.